When, for example, a plurality of copies of print data with the same structure are printed by a serial printer, printed sheets are ejected by being stacked at a given position on an ejection side. During the ejection of the printed sheets, the sheets are sorted for each copy or a plurality of printed sheets of the same page are stacked together. When printing a plurality of copies on a serial printer, therefore, the user manually separates the ejected sheets for each copy.
To simplify the sectioning of printed sheets that have been ejected together as described above for each copy, some serial printers have a sheet inverting unit that places ejected sheets with the printed surface either facing up or facing down. Other serial printer's prints change the sequence in which print data is printed each time one copy is printed so that copies are distinguished by a difference in printed surfaces.
To separate ejected sheets, a known printer uses a normal sort function that moves printed sheets to the right and left relative to the ejection direction and also switches between a feed tray in which print sheets are placed in a portrait orientation and a feed tray in which print sheets are placed in a landscape orientation each time one copy has been printed, with the print sheets being of the same size, each time one copy has been printed, as disclosed in Japanese Laid-open Patent Publication No. 2001-047690.
With a printer that may feed print sheets of the same size in the long-side direction and short-side direction, odd-numbered copies are fed in the short-side direction and even-numbered copies are fed in the long-side direction, as disclosed in Japanese Laid-open Patent Publication No. 11-199124.
A known shifter mechanism ejects printed sheets with an offset, which is made by an ejection roller, from a plurality of ejection positions that are set along a direction orthogonal to a sheet transport direction, as disclosed in Japanese Laid-open Patent Publication No. 2004-238120.
The serial printer carries out printing and ejection as a series of processes. The print head having head pins is placed to match the print position on the print sheet and moves in a primary scanning direction. The print sheet is transported in a secondary-scanning direction so that the print position moves to the next line and printing is carried out. With the serial printer, therefore, the position at which the sheet is placed is not changed during the printing process.
When a serial printer has, in a stacker, a mechanism that changes the sheet ejection position, the mechanism comes into contact with the sheet that is being printed, making it hard to change the ejection position. The mechanism may cause a print error. When printing processing is suspended during shift processing, a time loss may arise during printing processing. When a sheet inverting unit as described above is placed on, for example, a transport path that follows after print processing, the addition of a constituent part of this type may enlarge the printer and complicate the transport path. Since inverted print sheets are ejected at the same position on the stacker, confirmation of the sectioning position for each copy is desired.
In addition, with a serial printer, if the unit that changes the ejection position is set to operate automatically, control processing based on data to be printed is desirable.